At the origin of their injuries was a release of hydrogen peroxide vapor, “following the injection of hydrogen peroxide in a tank,” said Europe 1 prefecture of Haut-Rhin.

French power utility EDF, which operates the plant, said there had been a steam leak there but denied initial reports from the local fire brigade that a fire had broken out.

“No fire broke out,” an EDF spokeswoman said. “Steam escaped during a maintenance operation which set off the fire alarm,” she said, adding that the incident hurt two EDF staff.

Fessenheim, France’s oldest nuclear power plant, has two reactors that went into service in the 1970s. It operates in the Alsace region of France.

There are two 900 megawatt reactors at Fessenheim, which started up in 1977 and is on tap to shut down in the coming decade according to pledges made by Francois Hollande during this year’s French presidential election.

Environmentalists have raising concerns about the plant, especially since a nuclear accident caused by an earthquake in Fukushima, Japan, in 2011.

The plant is within 15 miles of towns in France, Switzerland, and Germany which have a combined population of 100,000.

Former French president Nicolas Sarkozy frequently pledged to keep Fessenheim open, saying closure would come “at the cost of jobs in the nuclear industry, the cost of our industrial competitiveness and the cost of our energy independence.”

Hollande promised to reduce France’s reliance on nuclear energy from 75 percent to 50 percent by shutting down 24 reactors by 2025.

Around 7:30 p.m., EDF then informed the French nuclear agency, Autorité de Sûreté Nucléaire (ASN), a defect on a primary pump seal led to a water leak above the normal values. However, dedicated circuits were able to collect the leak, officials said.

By the next day, EDF confirmed with ASN the leak stopped.

There were no injuries and no radiological consequences from the fire or subsequent pump leak. ASN provisional classification of the incident is at level 1 on the INES scale.

The Penly reactor will remain shut down until authorized for restart by ASN, which will undertake a technical assessment of the incident by ASN and its technical support organization the Institute for Radiological Protection and Nuclear Safety.

The primary pumps ensure the water circulation in the reactor primary circuit. In normal situation, a water injection inside some mechanical parts of the pump enables the cooling activity. This system consists of circuits dedicated to the collection of this water. At the Penly NPP, internal damages in the pump led to the collection of abnormal quantities of leaks, bigger than expected. The primary pumps are in the reactor building.

EDF said a faulty joint on a pump used to cool the reactor had caused a leak inside the reactor building. The joint suffered damage in the fire, which occurred after lubricant from one of the reactor’s cooling pumps spilled on the floor, generating smoke and small flames. The reactor automatically shut down after the fire and continued to cool normally.

Wednesday, December 28, 2011 @ 04:12 PM gHale

An inspection found tiny cracks on a penetration at the bottom of the fifth largest nuclear power plant in the world, Nord, France-based Gravelines 1’s reactor pressure vessel. The power unit will remain shut down until officials can repair the cracks.

In France’s 900-MWe class pressurized water reactors, some 50 small tubes around 38 mm in diameter penetrate the bottoms of the reactor pressure vessels. They allow for instruments to insert through the vessel and into the reactor core, but their construction is important to nuclear safety because it represents part of the boundary of the pressurized cooling system.

The tiny cracks are within the pressure vessel in the area of welded alloy around the tube at Gravelines 1. The Nuclear Safety Authority (Autorité De Sûreté Nucléaire, ASN) said it was the first time they found this type of defect in France, although officials found similar faults in 2003 at the South Texas Project site in the U.S.

EDF owns and operates Gravelines 1 along with France’s 57 other power reactors. The company suggested a repair method to the ASN, which is reviewing the technique in collaboration with the Institute of Radiological Protection and Nuclear Safety (Institut de Radioprotection et de Sûreté Nucléaire, IRSN). In the meantime, the reactor will remain offline, said ASN, noting the detailed 10-year inspection that discovered the issue had required the removal of nuclear fuel. The cracks therefore have no current impact on safety.

EDF has been requested by the ASN to check all its 900 MWe and 1300 MWe reactors for similar cracks, which consists of 54 units.